CLINICAL RESEARCH

Periprosthetic Bone Remodeling after 12 Years Differsin Cemented and Uncemented Hip Arthroplasties

Prakash Chandran MS, FRCS (Ortho),

Mohammed Azzabi MRCS,

Mark Andrews FRCS (Ortho), John G. Bradley FRCS

Received: 30 April 2011 / Accepted: 4 October 2011 / Published online: 21 October 2011

� The Association of Bone and Joint Surgeons1 2011

Abstract

Background Different patterns of stress shielding may

lead to differences in periprosthetic bone preservation

around cemented and uncemented hips in the long term?

Questions/purposes The purpose of this study is to

compare the difference in periprosthetic bone density

between cemented Charnley total hip and uncemented

hydroxyapatite-coated Furlong1 THAs at a minimum

followup of 12 years (mean, 16 years; range, 12–24 years).

Methods We studied a cohort of 17 patients who had

bilateral THAs with a cemented Charnley THA on one side

and an uncemented Furlong1 hydroxyapatite-coated THA

on the other side. At a minimum followup of 12 years,

Harris and Oxford hip scores were used to determine the

function, and dual-energy x-ray absorptiometry was used to

quantify bone mineral density adjacent to the prosthesis.

The results of the dual-energy x-ray absorptiometry scan

for cemented and uncemented hips were analyzed using

paired-sample two-tailed t-tests. To compare the Harris hip

scores, a nonparametric Wilcoxon test was used.

Results Bone mineral density was higher on the uncemented

Furlong1 side in Gruen Zones 2, 3, 5, and 6 of the proximal

femur and DeLee and Charnley Zone 1 of the acetabulum. In

all other zones, there was no difference. Comparison of Harris

and Oxford hip scores showed no differences between the two

hips.

Conclusion Bone density is better preserved around the

uncemented hydroxyapatite-coated Furlong1 stem compared

with the Charnley cemented stem.

Level of Evidence Level III, therapeutic study. See

Guidelines for Authors for a complete description of levels

of evidence.

Introduction

Periprosthetic bone behavior is complex and poorly under-

stood. Numerous studies have enumerated various patterns

of bone remodeling around cemented or uncemented hip

prostheses. There exists a major difference in bone remod-

eling between them [1, 8, 11, 13, 21]. Alterations of the

physiologic stresses around the hip contribute to the devel-

opment of subsequent adaptive remodeling to determine the

quality of the periprosthetic bone. Preoperative bone density

and mechanical characteristics of the implant, which

includes stiffness, rigidity, load transmission characteristics,

and the surface coating of the prosthesis determine the

homeostasis of the remodeled periprosthetic bone [3, 13, 16].

Commonly, there is a loss of 10% to 45% of the peri-

prosthetic bone mass during the first years after THA.

Studies have suggested this bone loss is not necessarily

Each author certifies that he or she, or a member of their immediate

family, has no commercial associations (eg, consultancies, stock

ownership, equity interest, patent/licensing arrangements, etc) that

might pose a conflict of interest in connection with the submitted

article.

All ICMJE Conflict of Interest Forms for authors and ClinicalOrthopaedics and Related Research editors and board members are

on file with the publication and can be viewed on request.

Each author certifies that his or her institution approved the human

protocol for this investigation, that all investigations were conducted

in conformity with ethical principles of research, and that informed

consent for participation in the study was obtained.

P. Chandran, M. Azzabi, M. Andrews, J. G. Bradley

Trauma and Orthopaedics, Scarborough General Hospital,

Scarborough, West Yorkshire, UK

P. Chandran (&)

15, Cresswell Close, Callands, Warrington,

North Cheshire WA5 9UA, UK

e-mail: prakachandran@yahoo.co.uk

123

Clin Orthop Relat Res (2012) 470:1431–1435

DOI 10.1007/s11999-011-2134-1

Clinical Orthopaedicsand Related Research®

A Publication of The Association of Bone and Joint Surgeons®

progressive and some degree of restoration of bone density

around implants occurs usually by 2 years [13, 19]. How-

ever, some studies have shown up to 40% loss in average

bone mineral content inside the lesser trochanter and 28%

loss in average bone mineral content 4.8 cm distal to the

lesser trochanter in the medial cortex. The data suggest that

the loss in mineral content may progress and could account

for as much as a 50% decrease in bone mass in the long term

[17]. The quality of periprosthetic bone determines the risk

of periprosthetic fracture and also defines the complexity of

revision surgery if needed. Better periprosthetic bone pres-

ervation can decrease the need for complex reconstruction.

Most studies reporting bone remodeling around cemented or

uncemented hip prostheses do not make a direct comparison

between them. Studying the long-term difference in

periprosthetic bone density between the cemented or

uncemented hip prostheses could help in choosing the bone-

preserving prosthesis for hip arthroplasty.

Dual-energy x-ray absorptiometry (DEXA) scans have

been widely accepted as a reliable tool with high repro-

ducibility to quantify bone mineral density (BMD) changes

adjacent to a THA [20]. It is a precise and an accurate

method of measurement for small changes in BMD around

femoral implants [4, 13–15, 26, 27].

We studied a cohort of patients who had bilateral THAs

with a cemented Charnley prosthesis on one side and an

uncemented hydroxyapatite (HA)-coated Furlong1 (JRI

Limited, London, UK) prosthesis on the other side. The

aims of this study were (1) to compare the difference in

periprosthetic bone density between cemented Charnley

and uncemented HA-coated Furlong1 prostheses at a

minimum followup of 12 years (range, 12–24 years); (2) to

assess if differences in periprosthetic bone density were

associated with differences in Harris or Oxford hip scores;

and (3) to compare radiographic signs of loosening.

Patients and Methods

Between 1980 and 1994, 22 patients had bilateral hip

arthroplasties with the cemented Charnley prosthesis on

one side and an uncemented Furlong1 prosthesis on the

other side. The Furlong1 prosthesis is fully HA-coated,

and the coating is applied by plasma spray with thickness

of 200 lm and bond strength of 40 Mpa. All surgeries were

performed by two senior authors (MA, JGB) using a sim-

ilar technique. At the time of study, five patients had died

and 17 were alive and were invited to participate in the

study. Seven of the patients were males. The mean age of

all patients at the time of assessment was 78 years (range,

62–93 years). The average time from cemented hip

arthroplasty to assessment was 18 years (range, 13–24

years), and the time from uncemented hip arthroplasty to

assessment was 14 years (range, 12–17 years) (Table 1).

We obtained local and regional ethical committee

approval.

We clinically assessed all patients by recording Oxford

and Harris hip scores. Standardized AP and lateral radio-

graphs were taken. The AP projection was centered on the

symphysis pubis and was taken at a standard distance of

1 m. We used Gruen zones [9] for the femoral component

and DeLee and Charnley [6] zones for the acetabular

component as references. The radiographs were assessed

for radiolucent lines, osteolysis, and endosteal bone for-

mation (spot welds) by one observer (PC); pedestal

formation was used to assess fixation and stability of the

uncemented stem (Fig. 1).

All patients had DEXA scans of both hips to determine

the quality of bone around the prosthesis. We collected

data regarding bone density and remodeling patterns. The

DEXA scanner used was a GE LUNAR prodigy ortho-

paedic scanner (GE Medical Systems Lunar, Milwaukee,

WI, USA), a narrow-angle fan-beam densitometer. We

used validated orthopaedic analysis software (GE Medical

Systems Lunar) solely to measure the periprosthetic bone

density excluding metal and cement artifacts; Gruen and

DeLee-Charnley zones were used as references and were

quantified in mg/cm2.

We analyzed the results from the DEXA scans using

paired-sample two-tailed t-tests. To compare the Harris hip

scores, a nonparametric Wilcoxon test was used. Pearson

correlations were done to examine the relationship between

the bone density measures (averaged for each zone) and the

quality-of-life measures.

Table 1. Comparative details of cemented and uncemented THAs*

Details Minimum Maximum Mean Standard

deviation

Age of patient at time of uncemented operation 54.4 80.3 65.2 7.9

Age of patient at time of cemented operation 38.4 79.4 59.6 9.9

Age of patient at time of scan 61.6 92.7 77.8 8.9

Time between cemented operation and scan 13.3 24.0 18.2 3.4

Time between uncemented operation and scan 12.2 16.8 14.6 2.6

* Data in years.

1432 Chandran et al. Clinical Orthopaedics and Related Research1

123

Results

DEXA scans showed the BMD was significantly higher

(p \ 0.05) on the Furlong1 side in Gruen Zones 2, 3, 5, and 6

of the proximal femur and DeLee and Charnley Zone 1 of the

acetabulum (Table 2). In all other zones, there was no

difference. Age was negatively correlated with bone density

in Gruen Zones 6 and 7 and acetabular Zones 2 and 3.

Comparison of Harris and Oxford hip scores showed no

statistically significant difference between the two hips

(p = 0.108).

All prostheses were well fixed, which included both

stems and the cups on either side. Radiographs showed

radiolucent lines in two Gruen zones in two cases around

the femur on the cemented Charnley prosthesis side. No

osteolysis, loosening, or migration of the prosthesis was

seen in any of the hips. In addition, 13 patients in the

Furlong1 uncemented group showed endosteal bone for-

mation (spot welds), and pedestal formation was observed

in 12.

Discussion

Periprosthetic bone remodeling is complex and poorly

defined, particularly with relation to the different cemented

or uncemented prostheses currently in use. In our study, the

comparative results revealed better preservation of peri-

prosthetic bone with the uncemented HA-coated Furlong1

prosthesis in Gruen Zones 2, 3, 5, and 6 on the femoral side

Fig. 1 A bilateral THA with a cemented Charnley prosthesis on one

side and the uncemented HA-coated Furlong1 uncemented prosthesis

on the other side is shown.

Table 2. Comparison of various zones between two sides (paired-samples t-test)

Zones Paired differences Significance

(two-tailed)Mean Standard

deviation

Standard error

mean

95% confidence interval of the difference

Lower Upper

Z1 cemented –

Z1 uncemented

�0.185 0.404 0.104 �0.409 0.038 0.098

Z2 cemented –

Z2 uncemented

�0.261 0.437 0.113 �0.504 �0.019 0.036

Z3 cemented –

Z3 uncemented

�0.413 0.516 0.133 �0.699 �0.126 0.008

Z4 cemented –

Z4 uncemented

0.106 0.292 0.075 �0.055 0.268 0.180

Z5 cemented –

Z5 uncemented

�0.420 0.301 0.077 �0.587 �0.253 0.002

Z6 cemented –

Z6 uncemented

�0.410 0.400 0.122 �0.600 �0.120 0.009

Z7 cemented –

Z7 uncemented

�0.160 0.599 0.154 �0.492 0.171 0.317

CZ1 cemented –

CZ1 uncemented

�0.188 0.146 0.037 �0.269 �0.107 0.004

CZ2 cemented –

CZ2 uncemented

0.009 0.220 0.056 �0.112 0.131 0.871

CZ3 cemented –

CZ3 uncemented

�0.008 0.285 0.073 �0.166 0.149 0.909

Z = Gruen femoral zones; CZ = DeLee-Charnley acetabular zones.

Volume 470, Number 5, May 2012 Periprosthetic Bone Remodeling in the Hip 1433

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and DeLee and Charnley Zone 1 on the acetabular side

when compared with the cemented Charnley prosthesis.

Our study has several limitations. It lacks the baseline

preoperative, postoperative BMD, and serial postoperative

measurements of bone density; these data would have

helped to identify longitudinal long-term changes resulting

from the implantation and subsequent remodeling and also

helped us to determine if the prosthesis has better preserved

or increased the BMD in the periprosthetic region. Our

primary aim was to compare the long-term difference in

periprosthetic bone density between the cemented and

uncemented HA-coated implants and the available data

helped us to make that comparison. The followup of the

patients who underwent cemented hip arthroplasties is

approximately 4 years longer than for the patients who had

the uncemented arthroplasties. Theoretically, the cemented

hip prostheses have been in place longer and therefore, it

might be expected that more bone was lost. Some studies

have shown remodeling in the periprosthetic region varies

with time and reaches homeostasis by approximately

2 years [1, 10] and few changes are expected later. Our

study involves observing long-term homeostasis in bone

remodeling and we believe the difference in timing of

implantation of cemented and uncemented implants would

not skew our results. Age has been found to negatively

correlate with bone densities in femoral Zones 6 and 7 and

acetabular Zones 2 and 3, suggesting older age is associated

with lower bone densities. The small sample size in our

study gives little power to detect such relationships. All

radiologic observations were made once by one observer

(PC), which could introduce interobserver and intraobserver

bias and adds to the limitation of the radiologic findings.

There are no long-term studies that directly compare

cemented and uncemented periprosthetic bone remodeling.

In the short term, up to 4 years [12], studies show that on the

femoral side, the cemented prosthesis induced bone mass

reduction in the lesser trochanter area and in the distal lateral

cortex and with the uncemented stem produced significant

bone resorption in the area of the lesser trochanter and in the

medial and the lateral distal cortex of the femur; both induced

an increase in the bone mass in the greater trochanter area. In

comparison, our study showed a different pattern of bone

remodeling with greater preservation of bone density in the

distal medial and the distal lateral cortex with the

uncemented stem. Longitudinal noncomparison studies with

Charnley cemented prostheses [5] have observed that at

1 year, there was a reduction in BMD of 6.7% in the calcar

region and an increase of 5.3% in the femoral shaft distal to

the tip of the implant [22]. Studies with an uncemented

HA-coated prosthesis [19] showed that the BMD was lower

in Gruen Zones 1 and 7 and concluded prosthesis design

influences periprosthetic bone loss. Similar studies with

HA-coated ABG prostheses showed bone density values

averaged between 96% and 113.8% for Gruen Zones 1 to 6,

and in Zone 7, there was a decline to an average of 72.1% at

24 months [24]. In contrast, one study [17] showed a 40%

loss of bone proximally and 49% distally at 7 to 14 years

[10]. In our study with the HA-coated Furlong1 prosthesis,

we observe preservation in the BMD in Gruen Zones 2, 3, 5,

and 6 of the proximal femur. The difference in periprosthetic

bone density observed in our study could be the result of the

mechanical properties and load transmission characteristics

of the prosthesis [25]. The femoral stems in the Furlong1

prosthesis transmit load largely in the metaphyseal-

diaphyseal region as compared with the Charnley prosthesis,

suggesting a stress-related remodeling pattern for long-

surviving prostheses.

On the acetabular side, the uncemented socket induced

bone resorption at the medial and caudal zones, and the

cemented socket showed significantly increased BMD in

the cranial zone [12]. Other studies with the cemented

acetabular component observed the periacetabular bone

mass returned to baseline values at 2 years with a pattern

suggesting uniform transmission of load to the acetabulum

[5]. Our study showed the BMD was better preserved in

DeLee and Charnley Zone 1 of the acetabulum. These

observations reflect the difference in load transmission of

the different socket designs suggesting a more uniform load

distribution with the Charnley cups as compared with the

screw-in design of the uncemented Furlong1 cups, which

probably had a higher load transmission in Zone 1 [23].

HA coatings induce bony ingrowth onto the surface of

the prosthesis; its influence on the periprosthetic BMD is

not clear. Although a fully HA-coated stem is expected to

induce greater bone apposition, wider trabecular struts, and

more connectivity compared with half HA-coated stems

[2], or tapered corundum-blasted titanium stems [1], it is

not clear if the HA coating has any role in better preserving

bone stock, with studies showing good bony integration

with uncemented nonbioactive surface implants [7, 18].

With good survival of the HA-coated Furlong1 cup and

stem [22], better preservation of periprosthetic bone would

potentially make revision surgery less complex and also

possibly decrease the risk of periprosthetic fracture.

Additional long-term studies of remodeling and peripros-

thetic bone density between cemented and uncemented

implants can help us understand preservation and behavior

of periprosthetic bone stock.

Bone density is better preserved around the uncemented

HA-coated stem in Gruen Zones 2, 3, 5, and 6 on the

femoral side and Zone 1 on the acetabular side compared

with the Charnley cemented stem.

Acknowledgment We thank Dr Jeremy Miles, senior lecturer in

biostatistics, University of York, for assistance with the statistical

analysis.

1434 Chandran et al. Clinical Orthopaedics and Related Research1

123

References

1. Aldinger PR, Sabo D, Pritsch M, Thomsen M, Mau H, Ewerbeck

V, Breusch SJ. Pattern of periprosthetic bone remodeling around

stable uncemented tapered hip stems: a prospective 84-month

follow-up study and a median 156-month cross-sectional study

with DXA. Calcif Tissue Int. 2003;73:115–121.

2. Al Hertani W, Waddell JP, Anderson GI. The effect of partial vs.

full hydroxyapatite coating on periprosthetic bone quality around

the canine madreporic femoral stem. J Biomed Mater Res. 2000;

53:518–524.

3. Ang KC, Das De S, Goh JC, Low SL, Bose K. Periprosthetic bone

remodelling after cementless total hipreplacement: a prospective

comparison of two different implant designs. J Bone Joint SurgBr. 1997;79:675–679.

4. Cohen B, Rushton N. Accuracy of DEXA measurement of bone

mineral density after total hip arthroplasty. J Bone Joint Surg Br.1995;77:479–483.

5. Cohen B, Rushton N. Bone remodelling in the proximal femur

after Charnley total hip arthroplasty. J Bone Joint Surg Br. 1995;

77:815–819.

6. DeLee JG, Charnley J. Radiological demarcation of cemented

sockets in total hip replacement. Clin Orthop Relat Res. 1976;

121:20–32.

7. Engh CA, Bobyn JD, Glassman AH. Porous-coated hip replace-

ment: the factors governing bone ingrowth, stress shielding, and

clinical results. J Bone Joint Surg Br. 1987;69:45–55.

8. Giannikas KA, Din R, Sadiq S, Dunningham TH. Medium-term

results of the ABG total hip arthroplasty in young patients.J Arthroplasty. 2002;17:184–188.

9. Gruen TA, McNeice GM, Amstutz HC. ‘‘Modes of failure’’ of

cemented stem-type femoral components: a radiographic analysis

of loosening. Clin Orthop Relat Res. 1979;141:17–27.

10. Kilgus DJ, Shimaoka EE, Tipton JS, Eberle RW. Dual-energy

X-ray absorptiometry measurement of bone mineral density

around porous-coated cementless femoral implants: methods and

preliminary results. J Bone Joint Surg Br. 1993;75:279–287.

11. Kobayashi S, Eftekhar NS, Terayama K. Long term bone

remodeling around the Charnley femoral prostheses. Clin OrthopRelat Res. 1996;326:162–173.

12. Korovessis P, Piperos G, Michael A. Periprosthetic bone mineral

density after Mueller and Zweymueller total hip arthroplasties.

Clin Orthop Relat Res. 1994;309:214–221.

13. Kroger H, Venesmaa P, Jurvelin J, Miettinen H, Suomalainen O,

Alhava E. Bone density at the proximal femur after total hip

arthroplasty. Clin Orthop Relat Res. 1998;352:66–74.

14. Laursen MB, Nielsen PT, Soballe K. DXA scanning of acetab-

ulum in patients with cementless total hip arthroplasty. J ClinDensitom. 2005;8:476–483.

15. Lekamwasam S, Lenora RS. Effect of leg rotation on hip bone

mineral density measurements. J Clin Densitom. 2003;6:331–

336.

16. Maistrelli GL, Fornasier V, Binnington A, McKenzie K, Sessa V,

Harrington I. Effect of stem modulus in a total hip arthroplasty

model. J Bone Joint Surg Br. 1991;73:43–46.

17. McCarthy CK, Steinberg GG, Agren M, Leahey D, Wyman E,

Baran DT. Quantifying bone loss from the proximal femur after

total hip arthroplasty. J Bone Joint Surg Br. 1991;73:774–778.

18. Park YS, Lee JY, Yun SH, Jung MW, Oh I. Comparison of

hydroxyapatite- and porous-coated stems in total hip replace-

ment. Acta Orthop Scand. 2003;74:259–263.

19. Rahmy AI, Gosens T, Blake GM, Tonino A, Fogelman I. Peri-

prosthetic bone remodelling of two types of uncemented femoral

implant with proximal hydroxyapatite coating: a 3-year follow-up

study addressing the influence of prosthesis design and preoper-

ative bone density on periprosthetic bone loss. Osteoporos Int.2004;15:281–289.

20. Sabatier JP, Guaydier-Souquieres G. Noninvasive methods of

bone-mass measurement. Clin Rheumatol. 1989;8(suppl 2):41–45.

21. Sharkey PF, Barrack RL, Tvedten DE. Five-year clinical and

radiographic follow-up of the uncemented long-term stable fix-

ation total hip arthroplasty. J Arthroplasty. 1998;13:546–551.

22. Shetty AA, Slack R, Tindall A, James KD, Rand C. Results of a

hydroxyapatite-coated (Furlong) total hip replacement: a 13- to

15-year follow-up. J Bone Joint Surg Br. 2005;87:1050–1054.

23. Shetty NR, Hamer AJ, Kerry RM, Stockley I, Eastell R,

Wilkinson JM. Bone remodelling around a cemented polyethyl-

ene cup: a longitudinal densitometry study. J Bone Joint Surg Br.2006;88:455–459.

24. Theis JC, Beadel G. Changes in proximal femoral bone mineral

density around a hydroxyapatite-coated hip joint arthroplasty.

J Orthop Surg (Hong Kong). 2003;11:48–52.

25. Turner AW, Gillies RM, Sekel R, Morris P, Bruce W, Walsh WR.

Computational bone remodelling simulations and comparisons

with DEXA results. J Orthop Res. 2005;23:705–712.

26. Venesmaa PK, Kroger HP, Miettinen HJ, Jurvelin JS,

Suomalainen OT, Alhava EM. Monitoring of periprosthetic BMD

after uncemented total hip arthroplasty with dual-energy X-ray

absorptiometry: a 3-year follow-up study. J Bone Miner Res.2001;16:1056–1061.

27. Wahner H. Technical aspects and clinical interpretation of bone

mineral measurements. Public Health Rep. 1989;104(suppl):27–30.

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